The testing of novel and alternative drive concepts for the propulsion or for ancillary components of aircraft is one subject matter of current research in the aviation sector. The propulsive drive system of the Airbus E-Fan is one example for an electrical drive system for aircraft; see https://de.wikipedia.org/wiki/airbus_e-fan, version of 12 Feb. 2016. The Airbus E-Fan is a two-seater electric aircraft by Airbus Group Innovations and serves for testing novel drive concepts. It is driven by two ducted propellers with a variable pitch that are respectively driven by electric motors. Lithium-ion batteries are accommodated in the wings for storing energy.
Efforts are being made to also use other electrical energy sources in addition to such batteries, such as solar cells and solar cell packs, photovoltaic modules, fuels cells or the like. Generally, electrical sources of energy of this type supply a direct voltage. For driving purposes, the direct voltage is frequently converted into alternating voltage in power inverters in order thus to drive electrical machines configured as alternating voltage machines—in particular alternating current motors.
Drives used in aircraft are frequently relevant with regard to safety. Therefore, most electrical drives in aircraft should therefore be designed in a redundant manner.
The current concept for achieving redundancy in electrical drive systems in aircraft is presented by way of example in FIG. 3. FIG. 3 shows several electric motors M1, M2, . . . , Mn for providing redundancy, each of which is supplied with electrical voltage by its own direct voltage source S1, S2, . . . , Sn via its own power inverter 18-1, 18-2, . . . , 18-n. Therefore, if there are, for example, three or four motors in order to provide drive redundancy, for example for a propulsion system, then, corresponding to the number of motors, the same number of transmissions for the propeller or the similar propulsion systems and the corresponding number of power electronic systems driving the respective motor are provided. This results in the need to accept a very large weight and also a cost disadvantage for providing the required redundancy as a safety buffer against the failure of a drive component.
With respect to the prior art, further reference is made to the following sources in literature:    [1] Jose Rodriguez, Senior Member, IEEE, Jih-Sheng Lai, Senior Member, IEEE, and Fang Zheng Peng, Senior Member, IEEE; “Multilevel inverters: A Survey of Topologies, Controls, and Application.”, IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, Vol. 49, No. 4, August 2002.    [2] DE 10 2014 203 563 A1    [3] DE 10 2014 203 553 A1.
In these sources, different concepts for power electronic circuits for electrical drive systems are described in fields other than aircraft technology.